I would like to know if the website_version module on the master branch is really under the GPL3 licence.

The module is downloadable on this page, which indicates that it's under GPL3.

https://apps.openerp.com/apps/modules/master/website_version/

Inside the files there is no licencing indication.

While I could assume the code is under GPL3 given those informations, I know that previous versions of the module have been under OPL (Odoo proprietary licence).

As such, I want to be 100% sure it's not an error and I can use the code however the GPL3 licence allows.